A318987 - OEIS

A318987

Number of semigroups of order n without identity.

1, 0, 3, 17, 153, 1687, 26397, 1596113, 3682361420 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,3`
	LINKS	`Table of n, a(n) for n=0..8.` `Index entries for sequences related to semigroups`
	FORMULA	`a(n) = A027851(n) - A058129(n).`
	CROSSREFS	`Cf. A027851, A058129.` `Sequence in context: A145081 A020562 A193161 * A353258 A208832 A135751` `Adjacent sequences: A318984 A318985 A318986 * A318988 A318989 A318990`
	KEYWORD	`nonn,more`
	AUTHOR	`Steve Szabo, Sep 06 2018`
	EXTENSIONS	`More terms from Joerg Arndt, Dec 09 2018` `a(0) prepended by Jianing Song, Oct 26 2019`
	STATUS	`approved`

Last modified May 26 12:47 EDT 2022. Contains 354091 sequences. (Running on oeis4.)